Authors

M Kolisko¹;  ¹ Institute of Parasitology, Biology Centre, CAS, Czechia

Discussion

Colpodellids are free-living marine, freshwater, and soil predatory microbial eukaryotes. They consume their prey through a unique process called myzocytosis, in which the predator attaches to and penetrates the prey’s surface and cell membrane and ‘sucks up’ the cell contents. These predators are closely related to Apicomplexan parasites and to two free-living algae, Chromera and Vitrella. All currently described colpodellids live aerobically and feed specifically on other microbial eukaryotes. Most apicomplexans are obligatory intracellular parasites that invade their host cells using a characteristic apical complex. Colpodellids also possess apical complex-like structures, despite the dramatic difference in life history compared to Apicomplexa. The apical complex of Colpodellids facilitates predation by myzocytosis, where attachment to the prey is followed by formation of a microtubule ring derived from the pseudoconoid that delimits the connection between the predator and prey. Overall, colpodellids together with Chromera, Vitrella and Apicomplexa represent an incredibly diverse group of organisms whose lifestyles range from primary production, through predation to parasitism. Moreover, they all share the apical complex that has been repurposed for different activities. We have recently discovered a colpodellid lineage containing isolates that break the paradigm inferred from all other known colpodellids, as they are bacterivorous and clearly capable of living both aerobically and anaerobically. Here, I will present morphological and molecular characterizations for several isolates of these novel Colpodellids, including light and electron microscopy observations demonstrating feeding behaviour and apical-complex structures. I will also show the results of phylogenomic analysis that pinpoints their precise phylogenetic position. Since these colpodellids are anaerobes, I will also show the results of in-silico predictions of mitochondrial and putative plastid metabolism. These results add to the existing diversity of life histories within colpodellids, apicomplexans, and chromerids.